James Hetfield, lead singer and guitarist for the heavy metal band Metallica, makes a straight-forward appeal for help in finding a fan's killer in a new public service ad produced for the FBI, Virginia and local law enforcement agencies.

Morgan Harrington, 20, was last seen alive on Oct. 17, 2009, when she left a Metallica concert at the University of Virginia in Charlottesville. As the FBI writes, "her remains were discovered the following January in a remote field on a farm in Albemarle County, Va."

Since then, DNA evidence has linked her murder to an unknown suspect in a September 2005 sexual assault in Fairfax, Va.

Along with the Hetfield video, authorities today released "enhanced" composite sketches of the suspect in that 2005 sexual assault.

There's a reward of up to $150,000 — $50,000 of it from Metallica — for information leading to the arrest and conviction of the person responsible for Harrington's murder.

"Remember, any information — no matter how small you might think it is — could be that crucial piece investigators need to help solve the case," Hetfield says in the new PSA.